This invention relates to a device and method for correcting the fuel amount in an internal combustion engine.
Because of the growing demand for minimising emissions from Otto engines an increasing amount of interest bas been shown in sequential computer controlled injection of fuel to the inlet valves. Sequential injection, where the fuel is injected individually for each cylinder to the inlet valve, where the cylinder is already in or at the beginning of the intake stroke, provides more precise dosing of the fuel before each combustion than if the fuel were to be injected simultaneously as soon as a cylinder is in the intake stroke. There are a number of patents on computer controlled sequential injection. In U.S. Pat. No. 4,785,784 and U.S. Pat. No. 4,961,411 two computer controlled injection systems are described in which two injections per cylinder take place for each intake stroke, and in which the second injection provides a correcting quantity if the fuel requirement has been changed since the first injection was initiated. The purpose of this is to ensure a faster response in transient load cases. The two-stage injection in these patents generally takes place as a split injection, and also mainly whilst the inlet valve is open.